1. Technical Field
The present disclosure relates generally to wheelchair designs and, more particularly, to wheelchair designs and related enhancements that include one or more of the following advantageous structural and/or functional features: an improved folding seat, interlocking/interchangeable footrests, a protective non-pinching hinge design, a multipurpose axle and axle plate system and/or right/left interchangeable armrest supports.
2. Discussion of Background Art
Standard wheelchair construction generally includes a welded tubular metal frame having seat and back elements of flexible material or fabric spanning the space between either side of the frame. Although foldable and of relatively light weight, such construction is inherently unstable and subject to weakening and breakage, predominantly at the weld locations and through the fabric elements. Furthermore, the initial construction and subsequent repair of such wheelchairs is expensive and requires technical expertise associated with bending and welding of tubular steel.
Foldable wheelchairs made from modular panels have also been proposed. For example, U.S. Pat. No. 4,625,984 to Kitrell discloses a folding wheelchair having two side frames connected by hinged foot and back panels. This design, however, includes a tubular metal framework in the side frames and requires that the seat be totally removed in order to fold. Furthermore, a wheel and belt motive system adds to the complexity of the construction.
U.S. Pat. No. 4,770,432 to Wagner discloses a foldable wheelchair constructed of panels of skinned polymeric foam which are secured together by piano type hinges. These hinges require continued maintenance and add to the skill and cost required in assembly and maintenance.
U.S. Pat. No. 4,917,395 to Gabriele discloses a wheelchair having a hinge construction between the side panels and seat and back panels which is an integrally molded part of the respective panels, providing both bearing and support surfaces. Although providing relative ease of assembly, such an integral hinge construction requires complete replacement of a panel should one portion of a hinge surface fail, thus increasing the cost of repair. Additionally, individual parts of this construction are not interchangeable from left to right.
U.S. Pat. No. 5,240,276 to Coombs discloses a foldable wheelchair construction with interchangeable right and left panels. The Coombs '276 design offers a simple and inexpensive construction for a wheelchair which may be assembled by relatively unskilled persons and which permits easy repair of broken parts. These parts include left and right side panels and at least two seat panels which together form the primary structure of the chair. The panels are made of a substantially rigid material, preferably injection molded polymer resin, and are held together in a chair configuration by means of interlocking fasteners. Additional frame stability is achieved by an interlocking pivotable lower support member, and a foldable stay member between the side panels. Wheels are attached in a conventional manner which permits vertical adjustment of the chair. The wheelchair of the Coombs '276 patent is easy to manufacture into a durable, rigid structure that virtually eliminates the primary causes of structural wheelchair failure, such as frame cracks, broken welds, fabric tears and chronic misalignment. The entire disclosure of the Coombs '276 patent is incorporated herein by reference.
Despite the highly advantageous features and functions of the wheelchair design(s) disclosed in the Coombs '276 patent, opportunities exist to improve upon features and functions thereof. The present disclosure is directed to wheelchair design enhancements having particular applicability to wheelchair(s) of the general type disclosed in the Coombs '276 patent. However, the design enhancements of the present disclosure are not limited to the wheelchairs of the Coombs '276 patent, but have wide applicability to wheelchair design and manufacture, as will be apparent to persons skilled in the art.